1. Technical field of the Invention
The present invention relates to a cotter-mounting apparatus for mounting a cotter to fix a retainer that regulates an incorporated position of a coil spring disposed around an axis, and in particular to a cotter-mounting apparatus for automatically mounting a cotter to fix a retainer, which compresses a valve spring of an engine and regulates the spring, at a valve stem.
2. Description of the Related Arts
Cotter-mounting apparatuses that are disclosed by, for example, Japanese Unexamined Patent Application Publications No. 2001-334430 and No. Hei-5-301133 have been known as prior arts.
The apparatus disclosed by the former Publication is provided with a guide pin having an outer diameter that is identical to the minimum inner diameter of a pair of cotters (a pair of collets), and a slider for reciprocally accommodating the guide pin, etc. When a valve stem is opposed to the guide pin and is elevated, a pair of cotters which are held by a retainer are pushed upward from the outer circumferential side of the valve stem and is caused to move to the outer circumferential side of the guide pin. Subsequently, the cotters are pushed and widened by the tip end of the valve stem and are held on the outer circumferential side of the valve stem. After that, the cotters are engaged with a single engagement groove.
On the other hand, the apparatus disclosed by the latter Publication is provided with a finger unit consisting of a cotter guide to place and hold a pair of cotters therein and a pair of finger members, and a retainer pushing member for holding a retainer in a state where a spring is compressed, etc. When the finger unit in which a pair of cotters are placed and held is moved downward in a state where the retainer is pushed down in advance by the retainer pushing member, the cotter guide is engaged with the tip end of the valve stem and is pushed upward, and at the same time, a pair of cotters are held by the outer circumferential side of the valve stem slid therein. After that, the cotters are engaged with a single engagement groove.
However, in an apparatus equipped with the finger unit, it is necessary that the cotters and retainer are separately provided, and the retainer is pushed and held in advance, wherein the apparatus is complicated, its incorporating procedure is cumbersome, and productivity thereof is decreased.
Also, in an apparatus in which the cotters are moved to the outer circumferential side by pushing to widen the cotters by the tip end of the valve stem while slidingly pushing the same upward, since the cotters are merely pushed to be widened and moved to the outer circumferential side of the valve stem, the state of the cotters may be made unstable, wherein there is a fear that the cotters are not securely mounted at a prescribed position.
Further, in the above-described two apparatuses, since the cotters are engaged with an engagement groove while causing the same to slide along the outer circumferential side of the valve stem, if a plurality of engagement grooves are provided, the cotters may be engaged with the first engagement groove and are not moved to the next engagement groove, wherein complete mounting is not enabled.
The present invention was developed in view of the above-described problems and shortcomings of the prior arts, and it is therefore an object of the invention to provide a cotter-mounting apparatus with a simple structure, which is able to mount cotters with a simple incorporating procedure or in a short time, and is able to securely mount cotters with respect to a plurality of engagement grooves.
In order to achieve the above-described object, a cotter-mounting apparatus according to the invention is a cotter-mounting apparatus for mounting a pair of cotters to fix a retainer, which holds a spring to exert a pressing force to an axial member in a compressed state, by causing the pair of cotters to be engaged with engagement grooves formed on the outer circumferential side of the axial member, which includes: a retainer holding mechanism that holds a retainer having a pair of cotters incorporated, and is driven to be relatively elevated and lowered on the upper side in the axial line direction of the axial member; a cotter separating mechanism for separating the pair of cotters from each other over the outer diameter of the axial member roughly in the horizontal direction while pushing up the cotters from downward and for holding the cotters; and a cotter pressing mechanism for pressing a pair of cotters separated by the cotter separating mechanism from the outside roughly in the horizontal direction and causing the cotters to be engaged with engagement grooves positioned in advance.
According to the above-described construction, where the retainer holding mechanism holds a retainer having a pair of cotters incorporated, the cotter separating mechanism separates the pair of cotters over the outer diameter of the axial member roughly in the horizontal direction (by a distance roughly identical to the outer diameter or spaced therefrom over the outer diameter), and the cotter pressing mechanism presses the pair of cotters so that the pair of cotters are brought near each other and causes the pair of cotters to be engaged with the engagement grooves of the axial member, which are positioned in advance. Thus, since the cotters can be mounted with a simple procedure, productivity thereof is increased, and since the cotters are not subjected to sliding along the axial member but are brought near each other roughly from the horizontal direction (from the outside in the diametrical direction of the axial member), it is possible to securely cause the cotters to be engaged with a plurality of engagement grooves.
In the above-described construction, such a construction may be employed, wherein the retainer holding mechanism includes: an elevation head that is driven to be elevated and lowered roughly in the vertical direction; a housing fixed on the elevation head, a part of which is brought into contact with the upper end side of the retainer; at least a pair of grasping arms, which are swingably supported on the housing so as to be brought near and spaced from each other roughly in the horizontal direction; and a first cam slider having a first cam portion for yielding a cam action to swing the grasping arms and being driven to be elevated and lowered and lower roughly in the vertical direction with respect to the housing.
According to the construction, when a pair of grasping arms are driven by the first cam slider in a direction along which the grasping arms are brought near each other, the retainer having a pair of cotters incorporated is grasped, and when the elevation head is driven downward, the retainer is positioned above the axial member (for example, a valve stem). Thus, since the pair of cotters and the retainer are held together, the structure can be simplified in comparison with a case where these are held separately, and its incorporating procedure can be also simplified. In addition, since a pair of grasping arms are driven by a cam action of the cam slider moving roughly in the vertical direction, the structure can be also made small-sized and integrated.
In the above-described construction, such a construction may be employed, in which the cotter separating mechanism includes: a push-up pin having an outer diameter equal to or greater than the outer diameter of the axial member, and for pushing up the pair of cotters from downward of the retainer held by the retainer holding mechanism; a guide pin reciprocally supported by the retainer holding mechanism, having an outer diameter equal to or greater than the outer diameter of the axial member, and having its lower end portion formed to be semi-spherical; and a spring for pressing the guide pin downward against a pressing force of the push-up pin.
According to the construction, when the push-up pin pushes up a pair of cotters from downward in a state where the retainer having a pair of cotters incorporated is held by the retainer holding mechanism, the pair of cotters is expanded outward roughly in the horizontal direction along the lower end portion of the guide pin while the guide pin is being pushed up with a prescribed resistance force brought about by the spring, and when the push-up pin is caused to descend thereafter, the guide pin is lowered by a pressing force of the spring, wherein the pair of cotters are held in a state where the cotters are separated from each other by a greater distance than the outer diameter of the guide pin, that is, the outer diameter of the axial member. Thus, it is possible to separate the cotters with a simple procedure, and it is possible to insert the axial member between the cotters while continuing the separation action and to cause the engagement grooves to be opposed to each other.
In the above-described construction, another construction may be employed, in which the guide pin and spring are disposed in a space formed at the cam slider. According to the construction, since the guide pin and spring are accommodated in the cam slider and disposed therein, integration of components can be achieved, and the apparatus can be simplified as a whole.
In the above-described construction, still another construction may be employed, which has a pressing member for pressing the pair of cotters pushed upward by the push-up pin, from upward to the retainer. According to the construction, since the pressing member presses the pair of separated cotters toward the retainer, the pair of cotters, which are in a state before mounting can be securely held in a separated state.
In the above-described construction, such a construction may be employed, in which the cotter pressing mechanism includes: at least a pair of pressing arms swingably supported with respect to the housing so that the pair of pressing arms are brought near and spaced from each other roughly in the horizontal direction; and a second cam slider having a second cam portion for yielding a cam action for causing the pressing arms to swing and being driven to be elevated and lowered roughly in the vertical direction with respect to the housing.
According to the construction, when a pair of pressing arms are driven to be brought near each other by the second cam slider, the pair of cotters are pressed and are engaged with engagement grooves of the axial member (for example, valve stem). Thus, since a pair of pressing arms are driven by a cam action brought about by the second cam slider moving roughly in the vertical direction, the structure can be made small-sized and integrated.
In the above-described construction, such a construction may be employed, in which the first cam slider may be concurrently used as the second cam slider. According to the construction, since the grasping arm and pressing arm are driven by a single cam slider, the structure can be made simple, wherein a grasping action and a pressing operation can be carried out at a prescribed stable timing.
In the above-described construction, such a construction may be employed, in which the first cam portion and the second cam portion are formed so that a releasing action of the grasping made by the grasping arm can be carried out at either of the timings, which are xe2x80x9cimmediately before a pressing action made by the pressing armxe2x80x9d, xe2x80x9cimmediately after the pressing actionxe2x80x9d or xe2x80x9csimultaneously with the pressing actionxe2x80x9d. According to the construction, time required for mounting cotters can be shortened, and productivity can be improved.
The other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.